1. Field of the Invention
The present invention relates to a driving method and a driving device for driving a display panel, and more particularly to the driving method and the driving device for driving the display panel which, when a liquid crystal display panel or a like is to be driven by using a plurality of timing controllers, put the driving being performed by one timing controller, for example, driving to be performed at time of the occurrence of an abnormality in display control, under control of any one of other timing controllers.
The present application claims priority of Japanese Patent Application No. 2005-061670 filed on Mar. 4, 2005, which is hereby incorporated by reference.
2. Description of the Related Art
In a conventional liquid crystal display device (hereinafter, referred to as a “known liquid crystal display device”), in order to achieve its displaying at high resolution, a technological method is generally employed in which two timing controllers are used for driving a liquid crystal display panel and a frequency of a dot clock signal is lowered. The known liquid crystal display device, as shown in FIG. 5, is so constructed that timing controllers 112 and 114 receive input image signals from corresponding signal inputting sections 24 and 26 respectively and supply signals for display control to corresponding source drivers 30, 32, 34, and 36 which drive a liquid crystal display panel (not shown) to display images corresponding to the input image signals on a screen of the liquid crystal display panel. In the known liquid crystal display device, when no signal is input to one timing controller, signals output from the one timing controller are not supplied to a driving circuit of a liquid crystal display panel. As a result, only a DC (Direct Current) component is applied to the liquid crystal display panel.
Also, technology is disclosed in Patent Reference 1 (Japanese Patent Application Laid-open No. 2001-272961) in which an abnormality in signals to be transferred from a display controlling section to a flat display body module in a flat display device, more particularly, in a liquid crystal display device, for example, the abnormality of stopping of a supply of a clock signal is detected and, based on the detected result, a form of the signal to be transferred to the flat display body module is changed, for example, a supply of a voltage among liquid crystal electrodes is stopped, that is, the voltage is reduced to zero.
Also, examples of methods for solving technological problems in a controller used in a driving method of a conventional liquid crystal display device are described in Patent Reference 2 (Japanese Patent Application Laid-open No. 2002-311913). That is, in the controller used in the driving method of the conventional liquid crystal display device, an interface is provided in which display data for one port is divided into display data for two ports and a liquid crystal display panel is driven by using the display data divided by the interface. However, in this case, following technological problems arise. In the above controller, a large constraint is placed on a data format to be transmitted to a liquid crystal display device from a transmitter of the data, in other words, a constraint is placed on freedom of a signal form of display data, which causes a constraint on freedom of circuit design and which leads, as a result, to complication, high pricing, or a like of the liquid crystal display device.
To solve the above technological problems, the liquid crystal display device disclosed in the Patent Reference 2 is constructed so as to have timing controllers to drive two groups of drivers which supply display digital data corresponding to 2N ports (N is a natural number) of the liquid crystal display panel when the liquid crystal display panel having a screen divided into a left half and a right half is driven and each of the timing controllers is made up of a data supplying circuit which supplies the first display digital data divided as time-series data or 2N-port second display digital data divided as data for a left half and as data for a right half of the screen corresponding to each different port, to each of the above 2N ports, of a memory circuit having a memory mounted between the data supplying circuit and the above two groups of drivers which writes the first display digital data supplied and reads the data as the second display digital data for 2N ports, and of an input selecting circuit to supply the above second display digital data selected out of the above first display digital data and the above second display digital data to be fed from the data supplying circuit to the above groups of drivers.
Moreover, a plural-screen display device is disclosed in Patent Reference 3 (Japanese Patent Application Laid-open No. Hei 6-102851) in which a screen is divided into a plurality of portions for being displayed. In the plural-screen display device, technological problems associated with ganged scrolling over the divided screens (hereafter called “partial screens”), movement of a cursor among partial screens, and improvement of operability are expected to be solved. To solve the problems technologically, the plural-screen display device is constructed so that display data corresponding to each of the partial screens is stored in a screen memory in a manner to correspond to the partial screens and, when a request for updating of the display data corresponding to the partial screen is made, a screen creating means can update the corresponding display data stored in the screen memory to display data for requested updating and, when a screen display instruction is input, a display data fetching means reads individually the display data for the partial screen and feeds the read display data to a screen display means corresponding to the partial screen and the screen display means corresponding to the partial screen to individually receive the display data for the partial screen performs processing of displaying the partial screen on a screen.
Also, a liquid crystal display device is disclosed in Patent Reference 4 (Japanese Patent Application Laid-open No. 2002-196733) in which a screen is divided into a plurality of portions for being displayed, as in the case of the Patent Reference 3. The liquid crystal display device uses an FPC (Flexible Printed Cable) to transmit image data to drive a liquid crystal display panel and various control signals. However, the FPC has technological problems. That is, as a frequency of a signal increases, signal coupling, noise, electromagnetic coupling, signal delay, signal distortion, or a like occurring in a transmission path of the FPC increase.
To solve these problems technologically, a timing controller is mounted for every source driver to individually drive a left half and right half of a liquid crystal display panel in a place close to each of the source drivers and an output signal of each timing driver is supplied to corresponding source drivers to drive the liquid crystal display panel. By configuring as above, the problems of signal delay and signal distortion occurring on the transmission path of the FPC are expected to be solved.
However, each of the above conventional technologies has problems. That is, in the case of the known liquid crystal display device described above, when no signal is input to one timing controller, an abnormality in display control occurs in the one timing controller and a supply of a signal output from the one timing controller to the driving circuit of the liquid crystal display panel is stopped. As a result, in this state, not only an abnormality in display occurs in the liquid crystal display device but also only the DC component is applied to the liquid crystal display panel, resulting in deterioration of the liquid crystal display panel. Moreover, no suggestion is provided about technological driving cooperation between one timing controller and the other timing controller.
Also, according to the technology disclosed in the Patent Reference 1, when an abnormality in signals to be transferred from the display controlling section of the flat display device to the flat display body module is detected, a form of the signal to be transferred from the display controlling section to the flat display body module is changed, for example, a voltage among liquid crystal electrodes is reduced to zero, which can avoid application of a DC voltage to the flat display body, for example, to the liquid crystal display panel and can prevent the liquid crystal display panel from deteriorating. However, there is no description of the case where the plurality of timing controllers is used as in the case of the known liquid crystal display device.
Also, according to the technology disclosed in the Patent Reference 2, there are provided the data supplying circuit, the memory circuit mounted between the data supplying circuit and the above two groups of the drivers which has a memory to write the first display digital data supplied and to read the data as the second display digital data for 2N ports, and the input selecting circuit to select the second display digital data out of the first display digital data or second display digital data to be fed from the data supplying circuit and to supply the selected digital data to the groups of drivers and, therefore, the technology serves to solve technological problems caused by a signal form of display data to be input, however, the technological problems associated with the use of a plurality of timing controllers remain unsolved as in the case of the known liquid crystal display device described above.
Also, according to the technology disclosed in the Patent Reference 3, display data corresponding to partial screens stored in a screen memory in a manner to correspond to the partial screens, when a request for updating of the display data corresponding to the partial screens is made, can be updated to display data for requested updating by a screen creating means and, when a screen display instruction is input, the display data for the partial screens is read individually by the display data fetching means and is fed to a screen display means corresponding to the partial screens and the screen display means corresponding to the partial screens performs processing of displaying the partial screens on a screen by using the display data for the partial screens, which serves to provide smooth ganged scrolling over partial screens, smooth movement of a cursor among partial screens and improvement of operability. However, the technological problems associated with the use of a plurality of timing controllers remain unsolved as in the case of technologies disclosed in the above Patent References 1 and 2.
Furthermore, according to the technology disclosed in the Patent Reference 4, the timing controller is mounted for every source driver to individually drive a left half and right half of the liquid crystal display panel in a place close to each of the source drivers and an output signal of each timing driver is supplied to corresponding source drivers to drive the liquid crystal display panel and, therefore, the problems of signal delay and signal distortion occurring in the transmission path of the FPC when a single timing controller is used for display control in the liquid crystal display panel as the conventional case can be solved. However, the technological problems associated with the use of a plurality of timing controllers remain unsolved as in the case of technologies disclosed in the above Patent References 1, 2 and 3.